Suppression of reproductive function in juvenile rams by a slow-release gonadotropin-releasing hormone implant.

Background: Regarding animal welfare and reversible suppression of reproduction the need for alternatives to surgical castration, like slow-release gonadotropin-releasing hormone (GnRH) implants, is increasing. Aim: In this study, we evaluated whether the onset of puberty can be suppressed by implantation of a slow-release GnRH implant (4.7 mg deslorelin) in juvenile rams. Methods: Seven juvenile rams (3-5.5 months) were treated with the GnRH analog deslorelin to analyze the effects on testicular development, sonographic findings of testicular tissue, testosterone concentration in the blood, spermatogenesis, and sperm parameters from the epididymis after castration. Seven rams of the same age without an implant served as controls. Results: Follow-up examinations were conducted over 5 months, after which four rams per group were castrated. No significant group differences were found in the andrological parameters on the group level, but testicular development was suppressed in three rams in the treated group. Histological examination revealed spermatogenesis in the testicular tissue in three of four animals treated with a GnRH analog. Conclusion: The onset of puberty in juvenile rams cannot be reliably suppressed by using the slow-release GnRH implant Suprelorin®.

Comparative study of electrocardiographic parameters in calves born after eutocia versus dystocia.

Background and Aim: The mortality rate of perinatal calves is high, particularly in dystocia cases. Besides detectable conditions such as trauma or amniotic fluid aspiration, the potential salience of cardiological diseases in neonatal bovine deaths has received little attention. This study aimed to compare the electrocardiographic parameters of calves born under conditions of dystocia and eutocia. Materials and Methods: Electrocardiographic, clinical, and laboratory diagnostic examinations were performed during the first 5 days of life on 40 calves. Of them, 20 calves were born under conditions of dystocia and 20 of eutocia. Results: Electrocardiograms (ECGs) did not show detectable arrhythmias in all calves. Both groups exhibited tachycardia on their first ECGs. The QT and ST interval durations developed differently over time in both groups, suggesting that these may be related to conditions of birth. Conclusion: The electrocardiographic differences between calves born of dystocia and eutocia could be a factor in the increased mortality rate of calves born of dystocia.

Differential expression of hemolysin genes in weakly and strongly hemolytic Brachyspira hyodysenteriae strains.

BACKGROUND: Swine dysentery (SD) is a diarrheal disease in fattening pigs that is caused by the strongly hemolytic species Brachyspira (B.) hyodysenteriae, B. hampsonii and B. suanatina. As weakly hemolytic Brachyspira spp. are considered less virulent or even non-pathogenic, the hemolysin is regarded as an important factor in the pathogenesis of SD. Four hemolysin genes (tlyA, tlyB, tlyC, and hlyA) and four putative hemolysin genes (hemolysin, hemolysin activation protein, hemolysin III, and hemolysin channel protein) have been reported, but their role in strong hemolysis is not entirely clear. Our study aimed to assess the transcriptional activity of eight (putative) hemolysin genes in a strongly hemolytic (B204) and a weakly hemolytic (G423) B. hyodysenteriae strain during non-hemolytic and hemolytic growth stages. RESULTS: Strongly and weakly hemolytic B. hyodysenteriae strains caused hemolysis on blood agar at different growth stages, namely during log phase (B204) and stationary/death phase (G423). During the lag, early log, late log (stationary phase in G423) and death phase (time points 1-4) strains differed in their hemolysin gene transcription patterns. At time point 1, transcription of the putative hemolysin gene was higher in B204 than in G423. At time point 2, tlyA and tlyC were upregulated in B204 during hemolysis. TlyB and hlyA were upregulated in both strains at all time points, but higher transcription rates were observed in the weakly hemolytic strain G423. The transcription activity of the hemolysin channel protein gene was quite similar in both strains, whereas the hemolysin activation protein gene was upregulated in the non-hemolytic stage of B204 at time point 4. Sequence analysis revealed deletions, insertions and single nucleotide polymorphisms in the G423 hlyA promoter, although without altering the transcription activity of this gene. CONCLUSION: Our data indicate a combined activity of TlyA and TlyC as the most probable underlying mechanism of strong hemolysis in B. hyodysenteriae. Further studies should verify if the expression of tlyA is upregulated by the putative hemolysin gene. Depending on their immunogenic potential TlyA and TlyC may serve as possible vaccine candidates, especially since vaccines for an effective control of swine dysentery are currently not available.

Monitoring of iron deficiency in calves by determination of serum ferritin in comparison with serum iron: A preliminary study.

Background: Iron deficiency can cause anemia in calves and is, therefore, of economic importance for the cattle industry. Low iron levels are commonly caused by feeding whole milk without the addition of dietary supplements and led to the most frequent cause of anemia in calves. Other reasons for the development of anemia include congenital iron deficiency, malnutrition, bleeding ulcers, or bloodsucking parasites. Aim: This study compared laboratory parameters that are commonly used to diagnose iron deficiency anemia in calves. Additionally, serum ferritin values were compared amongst calves fed different milk meals. Methods: For this purpose, blood samples from 40 calves were analyzed for different hematologic parameters as well as the content of copper, glutathione peroxidase, serum iron, and serum ferritin. Results: Eight calves showed decreased hemoglobin and hematocrit values and a significantly lower number of erythrocytes compared with non-anemic calves. Interestingly, 19 of 40 calves had a low serum iron. Considering their serum ferritin levels, only 14 calves, including six calves with both low iron and low ferritin levels, were classified as iron deficient. No direct correlation between serum ferritin and serum iron was detected. Comparing milk diets, more calves fed milk replacer showed reduced levels of ferritin compared with calves fed whole milk. Conclusion: Our data indicate that the determination of hemoglobin and serum iron is of limited suitability for the diagnosis of iron deficiency in calves. We suggest that the determination of serum ferritin should be the preferred parameter, since serum iron levels are subject to physiological fluctuation and a deficiency can be caused by inflammation or neoplastic diseases.

Phylogenetic diversity, antimicrobial susceptibility and virulence gene profiles of Brachyspira hyodysenteriae isolates from pigs in Germany.

Swine dysentery (SD) is an economically important diarrheal disease in pigs caused by different strongly hemolytic Brachyspira (B.) species, such as B. hyodysenteriae, B. suanatina and B. hampsonii. Possible associations of epidemiologic data, such as multilocus sequence types (STs) to virulence gene profiles and antimicrobial susceptibility are rather scarce, particularly for B. hyodysenteriae isolates from Germany. In this study, B. hyodysenteriae (n = 116) isolated from diarrheic pigs between 1990 and 2016 in Germany were investigated for their STs, susceptibility to the major drugs used for treatment of SD (tiamulin and valnemulin) and genes that were previously linked with virulence and encode for hemolysins (tlyA, tlyB, tlyC, hlyA, BHWA1_RS02885, BHWA1_RS09085, BHWA1_RS04705, and BHWA1_RS02195), outer membrane proteins (OMPs) (bhlp16, bhlp17.6, bhlp29.7, bhmp39f, and bhmp39h) as well as iron acquisition factors (ftnA and bitC). Multilocus sequence typing (MLST) revealed that 79.4% of the isolates belonged to only three STs, namely ST52 (41.4%), ST8 (12.1%), and ST112 (25.9%) which have been observed in other European countries before. Another 24 isolates belonged to twelve new STs (ST113-118, ST120-123, ST131, and ST193). The temporal distribution of STs revealed the presence of new STs as well as the regular presence of ST52 over three decades (1990s-2000s). The proportion of strains that showed resistance to both tiamulin und valnemulin (39.1%) varied considerably among the most frequent STs ranging from 0% (0/14 isolates resistant) in ST8 isolates to 46.7% (14/30), 52.1% (25/48), and 85.7% (6/7) in isolates belonging to ST112, ST52, and ST114, respectively. All hemolysin genes as well as the iron-related gene ftnA and the OMP gene bhlp29.7 were regularly present in the isolates, while the OMP genes bhlp17.6 and bhmp39h could not be detected. Sequence analysis of hemolysin genes of selected isolates revealed co-evolution of tlyB, BHWA1_RS02885, BHWA1_RS09085, and BHWA1_RS02195 with the core genome and suggested independent evolution of tlyA, tlyC, and hlyA. Our data indicate that in Germany, swine dysentery might be caused by a limited number of B. hyodysenteriae clonal groups. Major STs (ST8, ST52, and ST112) are shared with other countries in Europe suggesting a possible role of the European intra-Community trade of pigs in the dissemination of certain clones. The identification of several novel STs, some of which are single or double locus variants of ST52, may on the other hand hint towards an ongoing diversification of the pathogen in the studied area. The linkage of pleuromutilin susceptibility and sequence type of an isolate might reflect a clonal expansion of the underlying resistance mechanism, namely mutations in the ribosomal RNA genes. A linkage between single virulence-associated genes (VAGs) or even VAG patterns and the phylogenetic background of the isolates could not be established, since almost all VAGs were regularly present in the isolates.